In the manufacture of oriented strand board (OSB), the standard dryer, which has been used for many years, is a rotary dryer which utilizes flue gases from a boiler as the drying medium. Over the last five years or so, a limited number of conveyor dryers utilizing indirectly heated air as a medium have been manufactured, such as those by Proctor & Schwartz and George Koch Sons, Inc. These dryers operate at relatively low humidities which are related to the temperature conditions under which they are designed to operate. Examples of such dryers are disclosed in U.S. Pat. No. 5,524,361 and U.S. Pat. No. 5,341,580.
With conventional dryers, equipment must be utilized to detect and fight fires, which are not uncommon. In many installations, either to satisfy local regulations and/or to reduce operating costs, additional costly equipment must be utilized to control thermal and air pollution, to recover heat, and to increase the thermal efficiency of drying and drying rate. Furthermore, conventional dryers are not as fire proof, compact, or inexpensive to construct and operate as desired.